2. Stack Sum

#include <iostream>
#include <sstream>
#include <string>
#include <stack>
#include <queue>

using namespace std;

int main() {
    string line;
    getline(cin, line);

    istringstream ss(line);

    stack<int> numbers;

    int number;

    while (ss >> number) {
        numbers.push(number);
    }

    queue<string> q;

    while (true) {
        getline(cin, line);

        istringstream ss(line);

        string s;

        while (ss >> s) {
            q.push(s);
        }

        string command = q.front();
        q.pop();

        if (command == "end") {
            break;
        }
        else if (command == "add") {
            while (!q.empty()) {
                numbers.push(stoi(q.front()));
                q.pop();
            }
        }
        else {
            int num = stoi(q.front());
            q.pop();
            if (numbers.size() > num) {
                while (!numbers.empty() && num-- != 0) {
                    numbers.pop();
                }
            }
        }
    }

    int sum = 0;

    while (!numbers.empty()) {
        sum += numbers.top();
        numbers.pop();
    }

    cout << sum << endl;
    return 0;
}